WO2020046379A1

WO2020046379A1 - A heat transfer design for progressive heat transfer capability cooling channels

Info

Publication number: WO2020046379A1
Application number: PCT/US2018/049154
Authority: WO
Inventors: Jacob William HARDES; Timothy A. Fox
Original assignee: Siemens AG; Siemens Corp; Siemens Energy Inc
Current assignee: Siemens AG; Siemens Corp; Siemens Energy Inc
Priority date: 2018-08-31
Filing date: 2018-08-31
Publication date: 2020-03-05
Anticipated expiration: 2021-02-28

Abstract

A cooling channel arrangement for a region of a gas turbine engine is provided. The arrangement includes a cooling channel 26 having cooling sections 34, 36, 38 adapted for use in a component 24 with various component regions 28, 30, 32, with some sections having cooling flux mitigation adaptations to overcome the effects of increased temperature in the component regions to maintain efficient cooling effectiveness throughout the cooling channel sections. Adaptations may include regions of cross sectional area that increases heat transfer effectiveness, as well as regions characterized by an increase in lateral flow compared to longitudinal flow.

Description

A HEAT TRANSFER DESIGN FOR PROGRESSIVE HEAT TRANSFER CAPABILITY

COOLING CHANNELS

FIELD OF THE INVENTION

Disclosed embodiments are generally related to cooling channel arrange- ments, and, more particularly, to a cooling channel having features that increase cooling efficiency in a combustion turbine engines.

BACKGROUND OF THE INVENTION

In a combustion turbine engine, such as a gas turbine engine, combustion chambers combust fuel mixed with compressed air, and a hot working gas flowing from these combustion chambers is passed via respective transitions to respective entrances of the turbine, where energy in the working gas flow is converted into rotational energy. Often this rotational energy is used to generate electricity by coupling the turbine shaft with a generator.

Many of the components along the path taken by the hot working gas must be cooled to accommodate operation at the elevated temperatures desired to maximize the energy released from the fuel and carried by the hot working gas as it flows toward the exit of the engine. The operating temperature of many compo- nents varies by location, with single cooling channels, such as those shown sche- matically in Figure 2, often needing to accommodate relatively-cool temperatures at cooling channel entrances and relatively-higher temperatures at the channel exits, as shown schematically in Figure 2a. To avoid part failure, temperatures in the hottest areas of the components are kept at or just below allowable maxi- mums, with resulting temperatures in cooler regions being well-below component maximums, as shown in Figure 2a. Single cooling channel arrangements are avoided in areas with high thermal variances from channel exit to entrance, as they can operate with lost efficiency, as shown schematically in Figure 2c and Fig- ure 2d, respectively, as reductions in cooling flux and heat transfer capability “HTC”, often resulting in thermal stresses within cooled components.

In areas with few geometric constraints, groups of counter-flowing cooling channels, such as those shown schematically in Figure 3 may be used to increase cooling efficiency by reversing the coolant flow direction of adjacent cooling chan- nels, allowing adjacent cooling channels to bring relative homogeneity, counteract- ing the effects of coolant heating as the coolant in each channel flows from en- trance to exit, as shown schematically in Figure 3a. This beneficially maintains overall efficiency, as shown schematically in Figure 3c and Figure 3d, respectively, as balanced regarding cooling flux and heat transfer capability“FITC”, reducing overall thermal stresses in the cooled component.

Unfortunately, cooling arrangements with multiple, counter-flowing cooling channels are not suitable for all areas of gas turbine engines. Some components, such as plate fin areas of gas turbine combustor baskets and the exit region of combustor basket transition components, are too geometrically-restrained to ac- commodate the reversal of coolant flow in every second channel, leaving multiple, co-flowing arrangements, along with their associated inefficiencies and poor ther- mal performance as the common cooling approach.

What is needed is a cooling arrangement that provides efficient cooling in constrained regions where counterflow cooling is either not desirable or possible.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of the draw- ings that show:

FIG. 1 is a simplified schematic of one non-limiting embodiment of a com- bustion turbine engine that can benefit from aspects of the present invention.

FIG. 2 is a schematic illustrating one embodiment of a prior art co-flowing cooling arrangement.

FIG. 2a is a schematic illustrating the metal temperature vs. channel dis- tance within the embodiment of the prior art co-flowing cooling arrangement shown in FIG. 2.

FIG. 2b is a schematic illustrating cooling fluid temperature vs. channel dis- tance within the embodiment of the prior art co-flowing cooling arrangement shown in FIG. 2.

FIG. 2c is a schematic illustrating cooling channel cooling flux vs. channel distance within the embodiment of the prior art co-flowing cooling arrangement shown in FIG. 2. FIG. 2d is a schematic illustrating cooling channel heat transfer capability vs. channel distance within embodiment of the prior art co-flowing cooling ar- rangement shown in FIG. 2.

FIG. 3 is a schematic illustrating an embodiment of a prior art counter- flowing cooling arrangement.

FIG. 3a is a schematic illustrating the metal temperature vs. channel dis- tance within the embodiment of the progressive counter-flowing cooling arrange- ment shown in FIG. 3.

FIG. 3b is a schematic illustrating cooling fluid temperature vs. channel dis- tance within the embodiment of the prior art counter-flowing cooling arrangement shown in FIG. 3.

FIG. 3c is a schematic illustrating cooling channel cooling flux vs. channel distance within the embodiment of the prior art counter-flowing cooling arrange- ment shown in FIG. 3.

FIG. 3d is a schematic illustrating cooling channel heat transfer capability vs. channel distance within the embodiment of the prior art counter-flowing cooling arrangement shown in FIG. 3

FIG. 4 is a schematic illustrating one non-limiting embodiment of the pre- sent progressive heat transfer capacity cooling arrangement.

FIG. 4a is a schematic illustrating the metal temperature vs. channel dis- tance within the embodiment of the progressive heat transfer capacity cooling ar- rangement shown in FIG. 4.

FIG. 4b is a schematic illustrating cooling fluid temperature vs. channel dis- tance within the embodiment of the progressive heat transfer capacity cooling ar- rangement shown in FIG. 4.

FIG. 4c is a schematic illustrating cooling channel cooling flux vs. channel distance within the embodiment of the progressive heat transfer capacity cooling arrangement shown in FIG. 4.

FIG. 4d is a schematic illustrating cooling channel heat transfer capability vs. channel distance within the embodiment of the progressive heat transfer ca- pacity cooling arrangement shown in FIG. 4. FIG. 5 is a schematic illustrating one non-limiting embodiment of the pre- sent progressive heat transfer capacity cooling arrangement having moderate di- rection changes.

FIG. 6 is a schematic illustrating one non-limiting embodiment of the pre- sent progressive heat transfer capacity cooling arrangement having aggressive direction changes.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have recognized certain issues arising in connection with typical co-flowing and counter-flowing cooling arrangements (as shown in Figures 2 and 3, respectively, when used to cool components in geometrically- confined regions of combustion turbine engines 10, such as plate fin areas of gas turbine combustor chambers 16 and the associated exit regions of combustor bas- ket transition components 24, and have provided a cooling arrangement with im- proved cooling performance in those regions.

FIG. 1 is a simplified schematic of one non-limiting embodiment of a com- bustion turbine engine 10, such as gas turbine engine, that can benefit from as- pects of the present invention. Combustion turbine engine 10 comprises a com- pressor 12, a combustor 14, a combustion chamber 16 (such as a can-annular type), and a turbine 18. During operation, compressor 12 takes in ambient air and provides compressed air to a diffuser 20, which passes the compressed air to a plenum 22 through which the compressed air passes to combustor 14, which mix- es the compressed air with fuel, and provides combusted, hot working gas via a transition 24 to turbine 18, which can drive power-generating equipment (not shown) to generate electricity.

By way of overview, a cooling channel 26 according to one embodiment of the present invention includes several characteristics which make it suitable for use in geometrically-constrained regions (such as within a combustor 14) of tur- bine engines 10. As shown schematically in FIG. 4, cooling channel 26 includes three sections 34, 36, and 38, each having characteristics adapted to meet cooling requirements of three associated regions 28, 30, and 32 of a component (such as combustor 14) being cooled. In one embodiment of the present invention the first, second, and third component regions 28, 30, and 32 are spaced apart longitudinal- ly, and each region is exposed progressively hotter temperatures during operation of the turbine engine 10 of which the component is a part.

With continued reference to FIG. 4, first cooling section 34 is characterized by a relatively-straight path of nominal cross-section sized to allow fresh cooling fluid 40 passing into a cooling channel entrance 46 from a cooling fluid source (not shown) to maintain temperature in the cooled component first region 28 at a level designed to meet component life targets, as shown in FIG 4a. With additional ref- erence to FIG. 4b, FIG. 4c, and FIG. 4d, the cooling fluid 40 in section 34 has a relatively-low temperature (shown as cooling air temp in FIG. 4b), and acceptable level of heat transfer capability (shown as“FITC” in FIG. 4d) to cool the first cooling section at a design-efficient target rate (shown as cooling flux in FIG. 4c).

With continued reference to Fig. 4, the cooled component second region 30 is cooled by cooling channel second cooling section 36, which is characterized by “pinch points” or localized zones 48 having cross sections adapted to provide stra- tegically-positioned, localized pockets of increased heat absorption. These pinch points 48 may increase heat absorption though a variety of methods, including but not limited to, zones of decreased channel cross section area 50 and of coolant flow direction change 52. As shown with additional reference to FIGs 4, 5, and 6, direction change may be accomplished by a variety of switchback-style paths 54, with the direction changes varying in degree according to the level of local heat absorption increase desired, with sharper angles 58 providing more absorption than more gradual direction changes 60. This arrangement allows moderately- warm cooling fluid 42 passing through the cooling channel second section 36 to maintain temperature in the cooled component second region 30 at a level de- signed to meet component life targets, as shown in FIG 4a. With additional refer- ence to FIG. 4b, FIG. 4c, and FIG. 4d, the cooling fluid 42 in section 36 has an increased temperature (shown as cooling air temp in FIG. 4b), and increased level of heat transfer capability (shown as“FITC” in FIG. 4d) to cool the second cooling section at a design-efficient target rate (shown as cooling flux in FIG. 4c), even though this second component region 30 is exposed to increased temperatures compared to the component first region 28.

With continued reference to Fig. 4, the cooled component third region 32 is cooled by cooling channel third cooling section 38, which is characterized by an increased ratio of cooling channel volume with respect to component material.

This advantageously exposes an increased amount of material in the component third region 32 to cooling fluid 44, accounting for the reduced fluid-to-component- material temperature delta exhibited in this region 32 caused by the relatively-high temperature of cooling fluid 44 at this section 38 of the cooling channel. This in- creased density may be accomplished in a variety of ways, including but not lim- ited to an increase in lateral - as opposed to longitudinal - flow direction, so that the direction of cooling fluid 44 traveling through this region 38 has more lateral flow per unit of longitudinal flow than the first and second cooling sections. This arrangement allows relatively-hot cooling fluid 44 passing through the cooling channel third section 38 to maintain temperature in the cooled component third region 32 at a level designed to meet component life targets, as shown in FIG 4a. With additional reference to FIG. 4b, FIG. 4c, and FIG. 4d, the third cooling section 38 is exposed to increased temperature (shown as cooling air temp in FIG. 4b) compared to the component second region 30, yet exhibits an increased level of heat transfer capability (shown as“FITC” in FIG. 4d) to cool the third cooling sec- tion at a design-efficient target rate (shown as cooling flux in FIG. 4c) as the cool- ing fluid flows toward a channel exit 56. It is noted that this third section of cooling may also include pinch points 48 described above, and it would also be possible to increase the ratio of lateral flow to longitudinal flow within the second cooling 36.

While various embodiments of the present invention have been shown and described herein, it will be apparent that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.

Claims

CLAIMS What is claimed is:

1. A cooling channel arrangement for a region of a gas turbine engine, compris ing: a cooling channel 26 (having a first cooling section 28) adapted for use in a component 14 having a first region 28 spaced apart from a third region 32 by a second region 30 extending longitudinally therebetween, wherein said cooling channel includes a first cooling section 34 in fluid commu nication with a source of cooling fluid; wherein said cooling channel further includes a second cooling section dis posed in said component second region, said second cooling section being in fluid communication with said first cooling section and characterized by a second cool ing section cooling flux mitigation adaptation; wherein said cooling channel further includes a third cooling section disposed in said component third region, said third cooling section being in fluid communica tion with said second cooling section and characterized by a third cooling section cooling flux mitigation adaptation; and an exit in fluid communication with said third region; wherein said first and second cooling section flux mitigation adaptations are each effective to increase a cooling capacity factor of a cooling fluid passing through said second and third cooling section; whereby cooling capacity is kept substantially uniform through the cooling channel, from said entrance to said exit.

2. The cooling channel arrangement of Claim 1 , wherein said second cooling section cooling flux mitigation adaptation includes zones having cross sections adapted to provide localized pockets of increased heat absorption.

3. The cooling channel arrangement of Claim 2, wherein localized pockets are char acterized by decreased channel cross section area.

4. The cooling channel arrangement of Claim 3, wherein localized pockets are char acterized by coolant flow direction change.

5. The cooling channel arrangement of Claim 1 , wherein said third cooling section cooling flux mitigation adaptation includes a flow path having increased lateral flow aspects compared to longitudinal flow aspects.

6. The cooling channel arrangement of Claim 2, wherein said third cooling section cooling flux mitigation adaptation includes a flow path having increased lateral flow aspects compared to longitudinal flow aspects.

7. The cooling channel arrangement of Claim 6, wherein said third section cooling flux mitigation further includes zones having cross sections adapted to provide lo calized pockets of increased heat absorption.

8. A cooling channel arrangement for a region of a gas turbine engine, comprising: a cooling channel adapted for use in a component having a first region spaced apart from a third region by a second region extending longitudinally there- between, wherein said cooling channel includes a first cooling section 34 in fluid commu nication with a source of cooling fluid; wherein said cooling channel further includes a second cooling section dis posed in said component second region, said second cooling section being in fluid communication with said first cooling section and characterized by a second cool ing section cooling flux mitigation adaptation; wherein said cooling channel further includes a third cooling section disposed in said component third region, said third cooling section being in fluid communica tion with said second cooling section and characterized by a third cooling section cooling flux mitigation adaptation; and an exit in fluid communication with said third region; wherein said first and second cooling section flux mitigation adaptations are each effective to increase a cooling capacity factor of a cooling fluid passing through said second and third cooling section; whereby cooling capacity is kept substantially uniform through the cooling channel, from said entrance to said exit.

9. The cooling channel arrangement of Claim 8, wherein said second cooling sec tion cooling flux mitigation adaptation includes zones having cross sections adapted to provide localized pockets of increased heat absorption

10. The cooling channel arrangement of Claim 9, wherein localized pockets are characterized by decreased channel cross section area.

11. The cooling channel arrangement of Claim 10, wherein localized pockets are characterized by coolant flow direction change.

12. The cooling channel arrangement of Claim 8, wherein said third cooling section cooling flux mitigation adaptation includes a flow path having increased lateral flow aspects compared to longitudinal flow aspects.

13. The cooling channel arrangement of Claim 9, wherein said third cooling section cooling flux mitigation adaptation includes a flow path having increased lateral flow aspects compared to longitudinal flow aspects.

14. The cooling channel arrangement of Claim 13, wherein said third section cooling flux mitigation further includes zones having cross sections adapted to provide lo calized pockets of increased heat absorption.